Synthesis of Membrane Proteins and the "Signal Hypothesis"

Biochemical networks called signal transduction pathways convert specific patterns of synaptic transmissions into new protein synthesis. Ribosomal and RNA‐binding proteins are common targets of these pathways.

Synthesis of Membrane Proteins and the "Signal ..

Mechanism of Protein Synthesis (Explained With Diagram)

Formulation of the signal hypothesis was an outgrowth of protein synthesis and secretion research carried out at the Rockefeller University beginning in the late 1940s.

Mechanism of Protein Synthesis (Explained ..

The mechanism of protein translocation was established through the isolation and characterisation of SRP, the SRP‐receptor and the protein‐conducting channel.

Ribosomes and Protein Synthesis | Boundless Biology

They elicit robust, FPR-dependent calcium mobilization in human and mouse leukocytes and trigger a range of classical innate defense mechanisms, such as the production of reactive oxygen species, metalloprotease release, and chemotaxis.

Ribosomes and Protein Synthesis

The translation of several other mRNAs is known to be regulated through the 3'UTR, but this cannot yet be explained within the framework of known translational control mechanisms. A 34-nucleotide region of the 3'UTR of mRNA contains two regulatory elements, one that represses translation in germ cells and posterior cells of the early embryo, and one that inhibits repressor activity to promote translation in the embryo (). binds to this repressor element. is also expressed in anterior blastomere cells and is required for repression of mRNA translation (; ).

CH 40: The Mechanism of Protein Synthesis Flashcards …

Many of the translational mechanisms that have been well described and characterized in other organisms () have not yet been demonstrated in . These can be divided into two broad classes, modification of translation factors and modification of mRNA structure. However, the existence of homologous translation factors () and signal transduction components () suggests that previously discovered mechanisms operate in as well.

Mechanisms of Protein Synthesis by the Ribosome

The presence of in P granules () and its absence from initiation complexes () may represent another regulatory mechanism involving sequestration of a translation factor. A number of mRNAs have been found in P granules, some of which have been shown to be translationally controlled (). P granules also contain four GLH RNA helicases similar to eIF4A (; ). In , VASA is a germline-specific ATP-dependent RNA helicase, homologous to the GLH proteins, that is required for translation of at least two mRNAs, and , through interaction with eIF5B (; ). Also, eIF5A is required for localization (). The presence of all these translational components in P granules may signify regulation of germline-specific mRNA translation.

Mechanism of Protein Synthesis ..

Although there are many instances in which specific structures in the 3'UTR have been shown to affect translational efficiency in and other organisms (), the molecular interactions responsible for these effects are only partially understood. In oocytes, CPEB binds and sequesters eIF4E through an intermediary protein, Maskin (). In embryos, there is a similar interaction between the 3'UTR-binding factor Smaug and eIF4E, mediated by another protein, Cup (). However, in the translational component(s) involved in GLD-1-mediated regulation remain unknown (; ; ). The other 3'-terminal element, the poly(A) tract, increases the rate of translational initiation in yeast and plants due to the binding of PABP to a specific site near the N-terminus of eIF4G (; ; see ). Poly(A) stabilizes the PABP•eIF4G•eIF4E complex, which in turn leads to enhanced translational re-initiation (). As discussed below, there are several regulatory mechanisms in that involve changing the poly(A) length.

The signal for the termination of protein synthesis in ..

Mechanisms of regulation mediated by 5'-terminal structures remain largely unknown for . Both MMG- and TMG-containing mRNAs are found on polysomes (). In , mutations in the SL1 sequence alter efficiency of translation (). TMG-capped mRNAs are poorly translated in mammalian cell-free translational systems (), but a TMG-cap and SL stimulate translation in an translation system (). Interestingly, an optimal distance from SL to AUG for translational efficiency can be demonstrated in this system. The translational synergism between cap and poly(A) is greater for TMG than MMG. The well described translational regulator also interacts with 5'UTR sequences ().

Signal transduction - Wikipedia

A specific mRNA that undergoes regulated changes in poly(A) length is mRNA, whose translation must be repressed for male development. A possible mechanism of action is suggested by the observation that TGEs control the length of the poly(A) tract in a system (). Similarly, a 5-nt element in the 3'UTR of mRNA controls the length of the poly(A) tract (). must be downregulated to allow the switch from spermatogenesis to oogenesis. FBF and Nanos-3 interact with each other and repress translation of mRNA (). also physically interacts with FBF to interfere with FBF binding to the 3'UTR of mRNA (). promotes the transition from mitosis to meiosis together with the putative poly(A) polymerase. FBF also binds specifically to elements in the 3'UTR of mRNA and regulates expression ().